This section provides background information related to the present disclosure which is not necessarily prior art.
In oil well drilling operations, subsurface high pressure gas pockets can be encountered. A blow out preventer is required to prevent the release of the high pressure upwards through the drilling hole. Blow preventers are mounted in a housing surrounding a drill hole. Typical blow preventers have a resilient sealing means which can be caused to tightly grip the outer circumferential surfaces of various diameter drill string components to prevent pressure from subterranean gas pockets from blowing out material along the drilling string. Most oil well blow out preventers are remotely activated, as by a hydraulically actuated piston. Drilling activities are reaching into deeper and harder reservoirs and existing blow out preventer products are being challenged to function at higher temperatures and pressures. The conventional anti-extrusion barrier is designed to close on the largest diameter drill pipe and its operating range does not eliminate the gap in the anti-extrusion barrier which remains when closing on small pipe sizes. This gap is filled with compressed elastomer and is prone to be extruded at elevated temperature and pressure, causing a leak path for the contained fluids.